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Hi, I've just built my first Lightning 15 and there is no output. I wonder if anyone can help if i post pictures and give voltages.

Looking at tubes left to right inside chassis:-

V1 GZ34
Pin 2: 355v
Pin4: 292v
Pin 6: 292v
Pin 8: 356v

V2 EL84
Pin 2: 0
Pin 3: 12.3v
Pin 4: 3.41v
pin 5: 4.61v
pin 7: 365v
pin 9 363v

V3 EL84
Pin 2: 0
Pin 3: 12v
Pin 4: 2.921v
pin 5: 4.63v
pin 7: 369v
pin 9 366v

V4 12AX7
Pin 1: 160v
Pin 2: 93.3v
Pin 3: 94v
Pins 4+5: 4.72v
pin 6: 308v
pin 7: 76v
pin 8: 94v
pin 9 3.10v

V5 12AX7
Pin 1: 198v
Pin 2: 0v
Pin 3: 1.79v
Pins 4+5: 4.65v
pin 6: 353v
pin 7: 198v
pin 8: 199v
pin 9 3v

V6 12AX7
Pin 1: 154v
Pin 2: 0v
Pin 3: 2.90v
Pins 4+5: 4.59v
pin 6: 154v
pin 7: 1.62v
pin 8: 2.99v
pin 9 2.97v

Not sure how to attach pictures.

You got some funky voltages on your preamp tube's grids. I would look for shorts.

Is the 4.7V from pin to pin or from pin to ground?

All those voltages were pin to ground. Will look for shorts.

Heater voltages are AC not DC. Looks odd so please recheck.

Are these all measured with tubes in? Is the OT wired in? Impedance switch correctly wirred?

I would say the B+ looks OK and the voltages on the power tubes.

Check the jumpers under the board that they are going to the right places (do a continuity check).

Then Check values of all resistors feeding the plates. For example, V3 on the layout, which you call V4, should have practically the same voltage and you're measuring Pin 1: 160v and pin 6: 308v

Posting Pictures


BTW, it would be easier to refer to the tubes according to the layout.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

is there a voltage chart i can use to know when i have got it about right.

Is this a scratch build? Here's the docs you need?

viewtopic.php?t=859

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Yes, a combination of Trinity, Ceri@tone and using modified AC15 transformers with extra 5v filament winding for GZ34.

By the way, the 6.3v filament winding on the mains tranny is not centre tapped so i've used 2 x 100ohm resistors to ground. Would that give continuity from filament pins to ground? It does on mine.

Thanks for docs link.

Will comb through later.

You should get about 3.2V AC from each heater filament to ground with the 100 ohm ground reference.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

One filament is 3.1v and the other is 4.2 measured to ground.

I just can't seem to find the problem. I have hum coming from the speaker which goes up and down with the volume pot, but no signal at all.

I should clarify that it's the Trinity (Lightning) 15 i've made. Do you have voltages for that one?

If you have hum that is good.

Check for the signal getting shorted out/grounded. Sometimes the shield of the coax can short to the signal wire.

Same as the TC-15 ignore the EF86 (V7). See also viewtopic.php?t=151 in the resource section.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I gave up on this back in September last year and put it to one side, but after building a copy of a HC30 last week i went back to the Trinity 15 and after a lot of pulling apart and troubleshooting eventually discovered the problem - 1K pots had found their way into my 1M box - hence no output. Fixed now though and sounds great.

Next: TC-15.

...proving perserverance does pay off! Congrats!!

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps